My overall aim is to biochemically and genetically dissect the insulin gene transcriptional processes with special reference to repression of insulin gene expression. I have previously shown that the Adenoviral-5 Ela proteins inhibit pancreas beta-cell specific insulin gene transcription in vivo. The site of Ela-induced inhibition was within the rat insulin II gene enhancer element which is known to be required for tissue-specific expression of this gene. Accumulating evidence supports the hypothesis that cellular "Ela-like" activities are important in regulating cellular gene transcription. To test this hypothesis for the insulin gene, I will determine whether cellular and viral proteins, with functional properties similar to Ela, will repress insulin gene transcription. I have recently shown that both HeLa and liver cell nuclear extracts contain a cellular trans-acting transcriptional factor(s) capable of repressing insulin gene transcription in vitro. To understand how these viral and cellular repressor factors modulate insulin gene transcription, I propose to: (1) identify the target DNA site/region of the insulin gene required for repression; (2) determine whether the repressor factors interact directly with the same cis-acting sequences required for repression in vivo; and (3) identify the regions within the Ela polypeptide which are responsible for repression.